Initiatives in Digital
Technology: 2006–07 Funded Proposals

Deep imaging through biological tissue — especially when comprised of fat, skin and hemoglobin — has been virtually impossible with traditional methods for lighting. Traditional methods include continuous light from lasers, arc lamps, LEDs and tungsten-halogen. Strobe or flash lighting, on the other hand, when powered by transformers at 2400 watts/second or greater, and when focused and collimated via lenses, can penetrate through several centimeters of tissue at visible wavelengths, and even further at infrared wavelengths.

Lighting from strobe has not, to date, been explored for use with high quantum efficiency fluorescent labels directed at specific disease areas in biological tissue. Our initial results have shown that the body of a mouse can be penetrated by a high-powered strobe, even with violet light, the least penetrative visible wavelengths (data not shown). This has not been accomplished to date, except with relatively dim, bioluminescent probes.

In this proposal strobe lighting will be explored and characterized using a known fluorescent probe provided in cooperation with Li-Cor, Inc (Lincoln, Nebraska). The fluorescent probe (IRDye) excites at 790nm and emits at 810nm; ideal wavelengths for deep penetration, thus making it possible to label diseased areas and image affected tissue through the skin of a living animal.

Software will be developed to control both the commercial strobe unit and camera. This software will also include methodologies typically found in scientific imaging programs.

The strobe methodology is in the application process at the U of MN patents office, and proof of concept is needed for industry interest. The proposed imaging technology will reduce the need to sacrifice large numbers of mice currently required for imaging studies, facilitate real-time as well as time-course studies, and propel the development of new methods for imaging cancer and other diseases in humans.